duete; see due, ty 2 ]. syn: duty, obligation refer to something a person feels bound to do. A duty often applies to what a person performs in fulfillment of the permanent dictates of conscience, piety, right, or law: one's duty to tell the truth; a parent's duty to raise children properly.
Mutations in the RB1 gene are responsible for most cases of retinoblastoma. RB1 is a tumor suppressor gene, which means that it normally regulates cell growth and keeps cells from dividing too rapidly or in an uncontrolled way.
Symptoms of retinoblastoma include: 1  a white pupil (leukocoria) 2  misaligned or cross eyes (strabismus) 3  a different colored pupil in each eye. 4  eye pain caused by the development of glaucoma (less common)